This invention relates generally to an internal combustion engine and more specifically to a piston having a thermal regenerator attached therein.
Thermal regeneration has been developed for increasing the thermal efficiency of internal combustion engines. Thermal regeneration consist of the introduction of a heat exchanger within the engine. The heat exchanger includes a porous core that is capable of withstanding high temperatures. During the exhaust stroke of the engine, the core absorbs exhaust gas heat. The exhaust gas heat is then transferred from the core to working fluid (air/fuel mixture) following the compression stroke, but prior to or during the combustion of fuel.
A regenerative internal combustion engine is disclosed in U.S. Pat. No. 5,540,191 issued to Caterpillar, Inc. on Jul. 30, 1996, wherein a regenerator captures a portion of unutilized heat normally expelled with exhaust gas, and transfers the captured heat to the fresh working fluid. The above identified patent includes a regenerative member moveably positioned in the cylinder of the engine between the piston and the cylinder head. The regenerator is adapted to reciprocate in relationship to the piston movement.
Obstacles to using a regenerator as described above include the need to construct an internal combustion engine having an additional mechanism for moving the regenerator between the piston and the cylinder head. Previous designs required a separate reciprocating mechanism for moving the regenerator. The separate reciprocating mechanism requires additional features to be cast into the engine components, additional parts, a sealing arrangement to prevent compression loss in the cylinder and additional assembly time.
The above identified invention is directed to overcoming one or more of the above identified problems.
In an aspect of the present invention a piston assembly for an internal combustion engine is provided. The internal combustion engine includes a combustion cylinder, a predefined cycle including an intake stroke and a compression stroke. The piston assembly includes a piston head having a top surface. The top surface defines a recessed portion. A regeneration member having a porous structure is positioned within the recessed portion.
In another aspect of the present invention an internal combustion engine is provided. The internal combustion engine has a predefined cycle including a combustion stroke and an intake stroke prior to the compression stroke. The piston assembly having a top surface defining a recessed portion. A regeneration member is provided in the recessed portion and has a porous structure. The regeneration member is adapted to absorb heat from the combustion stroke and release the heat during the intake stroke.
In another aspect of the present invention a method for operating an internal combustion engine is provided. The internal combustion engine has a combustion cylinder and a predefined cycle including an intake stroke and an compression stroke. The method includes the steps of providing a regeneration member within a piston assembly, providing air to said combustion cylinder during the intake stroke, pushing an intake air through the regeneration member, introducing fuel, mixing fuel and intake air, igniting the fuel and intake air mixture, creating heat and absorbing heat with the regeneration member.